Watch: How to Save the Earth from Killer Asteroids by Using a Paintball Gun

What's the best way to knock a killer asteroid off a collision course with Earth? Ding-ding if you said "paintball gun."

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You’re suited up, mask in place, gas-powered marker loaded, primed for action. You maneuver the barrel of your weapon, lining up its reticle with your target, getting ready, taking aim…

Hey wait, isn’t that a planet-killing asteroid in your sights?

It could well be, if MIT student Sung Wook Paek’s idea sees light of day: spraying such an asteroid with a giant cloud of paint to knock it from its life-threatening course.

Say we detect a killer asteroid, something on a trajectory to collide with Earth and big enough to trigger an extinction event. We could try blasting it apart, but that risks creating collision fragments. We could try pulling it off course using a gravitational tractor, but that could take years and require ion thrusters. We could attach a rocket to the asteroid and try to push it off course, but the amount of force necessary to move an extremely large object could be prohibitive.

Enter Paek, a graduate student in MIT’s Department of Aeronautics and Astronautics, who proposes that we deflect such an asteroid with a simple paintball cloud, using the force of the ejected paint itself to initially nudge the asteroid, then counting on the paint’s solar reflectivity — all those bouncing photons — to gradually do the rest.

How? By sending up what amounts to a rocket-propelled paintball gun, the paint pellets crafted in space to avoid rupturing due to the force of takeoff. The spacecraft carrying this paint payload would approach the asteroid, then release volleys of pellets full of white paint powder (thus the paintball analogy), one round for the front side of the object, a second for the back.

According to MIT News:

In his proposal, Paek used the asteroid Apophis as a theoretical test case. According to astronomical observations, this 27-gigaton rock may come close to Earth in 2029, and then again in 2036. Paek determined that five tons of paint would be required to cover the massive asteroid, which has a diameter of 1,480 feet. He used the asteroid’s period of rotation to determine the timing of pellets, launching a first round to cover the front of the asteroid, and firing a second round once the asteroid’s backside is exposed. As the pellets hit the asteroid’s surface, they would burst apart, splattering the space rock with a fine, five-micrometer-layer of paint.

Why are we talking about Paek’s solution? Because it’s relatively unorthodox, of course, but also because his paper detailing the novel-sounding proposition recently won the United Nations-sponsored Move An Asteroid 2012 Competition.

The downside: Like a gravitational tractor, the process could take years to complete — Paek estimates up to 20 in his paper. The upside: Paek’s pellets could hold more than just paint, say you want to fire something else at the asteroid, or, according to Paek, “you could just paint the asteroid so you can track it more easily with telescopes on Earth.”